aldehydes

Another addition reaction involving a carbon nucleophile is the
Wittig reaction, in which an aldehyde reacts with a phosphorane (also called a phosphorus ylide), to give a compound containing a carbon-carbon double bond. The result of a
Wittig reaction is the replacement of the carbonyl oxygen of an aldehyde by the carbon group bonded to phosphorus. The German chemist Georg Wittig shared the...

work of Wittig

...involving carbanions, negatively charged organic species, Wittig discovered a class of organic phosphorus compounds called ylides that mediate a particular type of reaction that became known as the
Wittig reaction. This reaction proved of great value in the synthesis of complex organic compounds such as vitamins A and D
2, prostaglandins, and steroids.